1. Field of the Invention
The present invention relates generally to electrosurgical instruments, and more particularly to electrosurgical instruments having particular application for transecting organs, such as the cervix during a supracervical hysterectomy.
2. Background Discussion
There are approximately 650,000 hysterectomies performed each year in the United States, with 75% of these being abdominal hysterectomies and only 25% being vaginal hysterectomies. An abdominal hysterectomy is the removal of the uterus with or without the ovaries through an incision in the abdomen. A vaginal hysterectomy is the removal of the uterus with or without the ovaries through an incision in the vaginal area. Laparoscopic supracervical hysterectomy (LSH) is one alternative to total abdominal hysterectomy. In an LSH procedure, the uterus is removed using a laparoscope, but unlike in a total laparoscopic hysterectomy, the cervix is left in place.
Some of the potential advantages of laparoscopic supracervical hysterectomy include a shorter operation time, fewer complications, and an earlier return to normal activity, including sexual activity. A difficult part of the procedure, however, is the amputation or transection of the uterine cervix from the fundus, as the uterus is quite mobile and difficult to stabilize. The uterus does not provide much resistance to pressure during amputation, and, therefore, requires some type of traction during resection. Further, conditions are often far from optimal due to the angle of approach with the cutting electrode or scissors, and the proximity of neighboring crucial structures that are sometimes difficult to keep at a distance. Because of these difficulties, amputation of the cervix often takes from 30–45 minutes, or nearly half of the time of the entire procedure. The difficulty and length of time associated with performing this part of the procedure has caused reluctance among many physicians to adopt the procedure.
Current methods and devices used for transecting the cervix during an LSH procedure include bipolar needles, cutting diathermy, morcellator knife, laser energy, blunt scissors, monopolar energy with scissors, harmonic scalpel (ultrasonic excision), and reverse cervical conization. All of these known devices and methods suffer from similar drawbacks in that they do not provide a means for rapid and effective transection. This is primarily due to the fact that the cervix is more fibrous than tissues typically encountered, and thus is difficult to cut. Further, due to the mobility of the uterus, these devices and methods do not enable the surgeon to reliably and effectively maintain a transverse cutting plane at the desired location during resection. This is important because if the transection is made too high (too close to the uterus), some endometrium may remain, causing the patient to have a menstrual period even though her uterus has been removed.
Another known device and method for transecting the cervix during an LSH procedure is described in U.S. Pat. No. 6,176,858. The '858 patent describes a monopolar electrosurgical cutting instrument having a conducting wire that forms a loop around the organ to be amputated, and subsequently amputates the organ by applying high frequency monopolar current through the wire. The disclosed cutting apparatus includes insulated portions at each end of the wire that both must be grasped by a grasper. The graspers must be manually moved to manipulate the wire around the cervical neck to thereby encircle it. Then, the energized wire is pulled through the cervical neck by pulling on the grasper, which in turn pulls on the wire loop. One of the drawbacks of this device is that it utilizes monopolar energy, which requires careful attention to insulating all but the cutting portion of the wire from surrounding tissue, and therefore, requires a complicated insulated tube and introducer mechanism. Further, the use of monopolar energy does not adequately control the dispersion of energy in and around the device. Another drawback of this device is that to achieve amputation, pressure must be exerted by the wire on the organ and the wire displaced or moved in the cutting direction to transect the cervix. In other words, the wire must be pulled in a single direction against the resistance of the cervical neck to transect it. Thus, unnecessary movement of the organs and tissue occurs, which potentially can lead to inadvertent damage of these structures. In addition, such movement is particularly problematic given the mobility of, and need to stabilize the uterus as described above. The device of the '858 patent exerts significant unidirectional force on the cervical neck, and provides no means to stabilize the organs.
Accordingly, there is a need for an improved system and method for performing organ transection. There is a particular need for a surgical instrument and method for performing an LSH procedure that reduces surgical time and that is safer and easier to perform.